This clause first appeared in Issue 12 of our digital magazineCURIOUS .
Carl Sagan said : “ The cosmos is within us . We are made of whizz stuff . We are a means for the cosmos to make out itself . ” It ’s a quote so unbelievably good it get you stay up at night to take it all in . But of those words , lease ’s focus on two in particular : principal - stuff . Sagan did not in reality say stardust . Star - stuff might be a more undefined description , but , in a way , it is more exact . We are about to find out why .
On one mitt , you’re able to easy argue that we are made of stardust . or so 99 percent of the human body is made of just six component . In decree of fraction of mass , they are : O , carbon , H , nitrogen , calcium , and phosphorus . Around 65 percent of your mass is from atomic number 8 , 18.5 percent from carbon copy . Hydrogen makes up 90 pct of all atoms and is the only component in the human body that does not come from stellar processes or events .
To make a human from scratch
To find the stemma of hydrogen , we need to start at the verybeginning of the creation . Within a few moment following the Big Bang , the cosmos was experiencing nucleosynthesis . The whole seeable world a few transactions after the Big Bang was relatively diminished . If we centered it from the Sun , it would not stretch much further than afew dozenof the closest maven system . And it was blistering , a state call in quark - gluon plasma . quark are the second that make protons and neutrons , the particles at the center of atomic nuclei , and gluons make them flummox together .
The universe was undergo massive expanding upon , and as it became larger , it also became cooler – at least cold enough for protons and neutron to pop into existence . Hydrogen in its simplest contour is just a individual proton , so as the proton emerged from the quark - gluon plasma , voila , you bugger off hydrogen .
Some of the calcium in your bones and atomic number 26 in your blood would come from the destruction of these star .
The less vulgar form of hydrogen is predict heavy hydrogen , which has one proton and one neutron , and this ended up fusing into helium ( two proton and two neutrons ) and a tiny amount of other constituent but nothing as heavy as carbon copy ( in its most common form , six protons and six neutrons ) . At that head , the universe was 75 pct hydrogen and 25 per centum helium ( plus traces of other elements ) .
To make carbon and anything heavier , you ’d ask another source of nucleosynthesis : stars . Stars create heavier elements than hydrogen and helium by nuclear fusion . First hydrogen is release into helium , then helium into atomic number 6 and O , and then heavier element if the star is massive enough .
When they get to smoothing iron , the system breaks down . It take more energy to fuse iron than you get out . Without the free energy product , the wizard tumble on itself , making more element in the process and spreading those elements around the existence as it explodes in a supernova .
These violent ends have violent delights
To make us , you need all of that . Not just the Big Bang , not just star fusing elements ; you also need their organic evolution and eventual death , particularly in the most dramatic and explosive style .
Some component are farm in the explosion of white dwarfs . White dwarf are principal that were not massive enough to go supernova by themselves , so their collapsed magnetic core cease up exposed . But if they have a companion , they might slip enough material to bilk a critical threshold and go boom – in the process creating new elements . Some of the atomic number 20 in your bones and iron in your blood would come from the death of these stars .
The last outgrowth that forms the heavier natural elements in the occasional table is neutron star collisions . It ’s the only way you’re able to have the rapid neutron seizure , also known as the r - procedure . This is a set of atomic reactions that make half of the elements that are grueling than iron . It is responsible for for stuff such as Au and atomic number 78 , but also for elements fundamental to human physiology . The all-important contribution of neutron star collisions to our composition is iodine . There is not much , but it ’s a key element for our metabolism .
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So , to make us , you need all of that . Not just the Big Bang , not just star fuse element ; you also take their evolution and eventual death , especially in the most dramatic and explosive manner . You postulate magnanimous stars and small stars . Maybe even the braggart sensation that ever existed , objectsup to 10,000 timesthe volume of our Sun that lived for just 2 million age at the very dawn of hotshot establishment in the universe of discourse .
With all of this in mind , it is quite obvious we are made of star - stuff and nonsense . We are here because stars have died . But the question we ’re address is slightly different : are we made of stardust ? The answer is partially – and now this is where we can properly nerd out .
Dust to dust, ashes to ashes
Stardust , cosmic detritus , extraterrestrial dust – whatever you need to call it , the macrocosm is peppered with it . But it ’s not like Earth dust . First of all , it ’s commonly much finer , mostly between the consistency of smoke and structures made of just a handful of molecules . The biggest structures are micrometeoroids about 100 microns across ( around 0.1 millimeters ) . And here we get to the issue : stardust has a very specific significance in astrophysics .
Everything around you comes from virtuoso . We are the product of those cosmic interactions .
It is dust created by star , but not all dust is created there . So , it is a nitpicking parameter but it is an significant one . Firstly , it ’s interesting to know that some stars created molecules , even some complex carbon - based single . maven make these molecules and they are then ejected into space . Some carbon molecules might finally find oneself their way to planets , where they might be used as the construction stop of populate things .
So you see , we are stardust , but only in part . Acommon estimateof how much whiz directly lend to all the dust in the population is around 6 percentage . This mightseemlike a disappointing number , but we ’re lead to argue that it ’s not . Being nitpicky about the question “ are we made of stardust ? ” earmark us to easily appreciateall the sourcesthat eventually made our planet and , in time , us .
Cosmic junk is create near headliner , as they lose the knocked out layer of their atmospheres . It is created in the boot out material of novae , the ephemeral state where uranologist observe the sudden brightening of a white dwarf stealing material from a associate star . And of class , as supernovae explode , rubble also forms in the ejecta of these cataclysmic events .
From the stars to our bodies
rubble is then processed in the interstellar sensitive , the matter that exists in the space between maven . Here , dust can be destroyed and reconstituted , it can be turned into something newfangled . The interstellar metier is filled with complex atom such as polycyclic redolent hydrocarbons , herald molecules to important organic fertilizer like amino acids , the building block of proteins . The evolution of these dust grains hap not only when star are dying or have die , but also at their birth .
“ sensation stuff and nonsense ” is more matter - of - fact and less defined , but it encompasses all the shades of the starring processes that directly or indirectly ended up making us .
acute energy from the protostellar stage can create a response in the cloud of flatulence and detritus that palisade a fledgling lead . Those processes will eventually pass the grains of rubble to interact with others , to conglomerate into pebble , and from pebbles to planets – well , it ’s just a short whole step in cosmic term . Everything around you comes from stars . We are the product of those cosmic interaction .
But there is a speck that we have not view yet , not precisely stardust but stardust adjacent ( sometimes literally attached to it ): water . Water ice is a by-product of star formation and it is the most vulgar self-coloured material in the world .
The water in our rivers , sea , drinks , and bodies constitute long before the Solar System in the cooler parts of interstellar blank space where it can condense . But water vapor can also form in nerveless stars , those that have a temperature less than the value that have water molecules to split . So , among that dust release by stars , there ’s also water supply . piss that eventually found its elbow room to Earth and to us .
Stuff is better than dust
We are a dispiritedly romanticistic species . “ Stardust ” to us has connotation of something sparkly and magical , like pouf dust ; a sprinkling of cosmic magic that relieve oneself it a bit more limited . “ Star poppycock ” is more matter - of - fact and less defined , but it comprehend all the sunglasses of the starring process that directly or indirectly ended up ca-ca us .
Maybe “ hooey ” has less magical connotations but the grit of it has more mightiness . star burned to make us , became giants , and blend in supernova . The dense stars in the universe merged to make bits of us , and the molecules that make us take form in burn atmospheres and freezing interstellar clouds . We are headliner - stuff , a patchwork of elements and molecules formed in a huge smorgasbord of cosmic environments . But we are more than just dust or hooey , we are the sum of cosmopolitan processes that make out together in what we call a human being .
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